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i&1111% <br />•E ENGINEERING <br />is able to monitor the performance of the excavation and modify his activities to reflect varying <br />conditions. In all cases, cut -slope inclinations should conform to applicable governmental safety <br />guidelines. <br />Slope Protection <br />Regardless of inclination, temporary slopes should be protected from surface -runoff erosion. Typically, <br />this can be accomplished by means of berms or swales located along the top of the slope, and possibly <br />by means of plastic tarpaulins placed over the slope. <br />4.3 SEISMIC DESIGN PARAMETERS <br />The 2015 International Building Code (IBC) seismic design section provides a basis for seismic design of <br />structures. Computation of forces used for seismic design for this code is based on seismological input <br />and site soil response factors. Ground motions considered for evaluation using these guidelines are <br />defined as motions with approximately 2 percent probability of exceedance in 50 years, or about a 2,500- <br />year return period. <br />Characterization of soil profile type is required in the IBC to determine the site class definition. Based on <br />the dense nature of Vashon TII deposits and soil classifications derived from the explorations completed <br />at the site, the site could be classified as Site Class D. The spectral response accelerations were obtained <br />from the USGS Earthquake Hazards Program for the project latitude and longitude. Table 2 below <br />provides seismic design parameters for the site that are in conformance with the 2015 IBC. <br />Table 2. Seismic Design Parameters <br />Site location <br />Latitude= <br />48.005954 <br />Longitude= <br />-122.20322 <br />Recommended Site Class <br />D <br />Seismic Design Code <br />IBC 2015 <br />Structural Analysis: <br />Risk -targeted NICE (MCER) <br />Mapped Spectral Response Acceleration <br />Parameters <br />(Site Class B) <br />Short -Period, Ss= <br />1.264g <br />1-second Period, S, = <br />0.4819 <br />Site Coefficients <br />Short -Period, Fa = <br />1.0 <br />Long -Period, F. <br />1.519 <br />Spectral Response Acceleration <br />Parameters Adjusted for Site Class <br />Sets=FazSs= <br />1.264g <br />Sett=F.x Si= <br />0.7319 <br />Design Spectral Response Acceleration <br />Parameters <br />Sos= 2/3 x Sets = <br />0.842 g <br />Sot=2/3 x Sett= <br />0.487 <br />MP ENGINEERING, PLLC MPGEOTECH.COM <br />